Bondo Fiberglass Resin Jelly features a resin that is reinforced with milled fiberglass for a thicker consistency. More firm but still workable, it provides smooth, drip-free application. It can be used in small holes and minor rust-outs without backing strips, cloths and mats. This waterproof fiberglass resin jelly is especially suitable for vertical surfaces on autos and boats.Bondo Fiberglass Resin Jelly features a resin that is reinforced with milled fiberglass for a thicker consistency. More firm but still workable, it provides smooth, drip-free application. It can be used in small holes and minor rust-outs without backing strips, cloths and mats. This waterproof fiberglass resin jelly is especially suitable for vertical surfaces on autos and boats.